1. Field of the Invention
The present invention relates to an image processing apparatus, an image forming apparatus, and an image processing method.
2. Description of the Related Art
Techniques are conventionally known for correcting density values of input image data in order to eliminate image defects such as streaks (which hereinafter may be referred to as “vertical streaks”) produced in the same direction as the feeding direction of a recording medium (for example, paper) in an image forming apparatus.
For example, Japanese Patent No. 4661376 discloses a technique for correcting density values of input image data by obtaining not only the tone characteristic (relation between the input tone value and the output tone value) of each primary color in printing an image of primary colors (basic constituent colors) but also the tone characteristic of each primary color in printing an image of multi-primary colors in which a plurality of basic constituent colors are superimposed on each other, and then creating a correction table based on the obtained characteristics.
However, the technique disclosed in Japanese Patent No. 4661376 requires an enormous amount of test patterns to be formed and an enormous amount of operations, because it is necessary to form an image of a test pattern for every combination of primary colors to obtain the tone characteristic of each primary color and then to create a correction table based on the obtained characteristics.